Breeding And Fermentation Of PSP Yielding Strains

Yunzhi polysaccharopeptide (PSP) is the main active ingredient extracted fromthe mycelium of Coriolus versicolor. It has proved that PSP could enhance ourimmunity, so it is widely used in adjuvant treatment of cancer. In this paper, westudied on the strain screening, morphology of mycelium and fermentation processoptimization of Coriolus versicolor.The fruiting bodies of Coriolus versicolor were obtained by artificial cultivation.Spores were isolated from the mature fruiting bodies, and cultured on PDA at thetemperature of28℃for48hours. Many colonies of different spores were greatdifferent from the original strain Cov-1both of morphology and diameter on PDA.Several typical strains in different morphology were obtained by screening. Theshape of mycelium pellet that isolated from the zymotic fluid was observed by bothnaked eye and paraffin section and photomicrography technique. PSP was extractedand its quality was also examined. As a result, the morphology of mycelium pelletfrom various strains was different, which eventually influence the biomass, the yieldof PSP, and the sugar content and monosaccharide composition of PSP. The optimizedstrain PT00407, which was of dense colony and a lot of aerial mycelium on PDA, hadthe highest yield of PSP, the highest level of total sugar content and molar percentageof glucose of PSP. In order to find the relationship among the fermentation time, theshape of mycelium pellet and the yield and the quality of PSP. The liquid stains andthe fermentation liquor at30,60,66and72hours were obtained and observed byparaffin section and photomicrography technique.The fermentation liquor was alsoexamined.As a result,the yield of PSP was increasing and the level of total sugarcontent of PSP was decreasing in the process of the fermentation. The bestfermentation time was determined at72hours after the comprehensive consideringin the aspect of yield and quality of PSP. Under this condition, the yield and the totalsugar content of PSP were1.5g/L and45.43%respectively. This study is helpful todetermine the fermentation process parameters to produce PSP.The process parameters were optimized in the submerged fermentation of Coriolus versicolor in stirred-tank bioreactor. The optimized strain PT00407was usedas seed and the liquid medium has been optimized in previous studies. The totalamount of carbon and nitrogen of the medium is6.9%, and other fermentationprocess parameters are as follow: the inoculation volume is10%, the capacity of thetank is at80%, the initial rotation speed and ventilation of the fermentation is at200rpm and0.5v/v/min respectively. Orthogonal design method was used to optimizethe fermentation process parameters，including pH, dissolved oxygen tension（DOT）,temperature and time. The four parameters which had been optimized and the bestcombination was A1B2C3D3: The pH was4.0.The dissolved oxygen tension（DOT）was20%. The incubation temperature was30℃. The culture time was72hours. Asthe result, The biomass and PSP content of the fermentation was23±1.06g/L and1.99±0.17g/L respectively. The sugar and protein content of the polysaccharide was37.82±0.46%and21.45±0.38%respectively. The proportion of the PSP with theweight average molecular weight greater than or equal to40000Dalton was51.4±0.72%. The result illustrated that PSP is up to the national standards.